Transcript Swiss needle cast multiplier for ORGANON

Development of Swiss Needle Cast
diameter and height modifier for
ORGANON
Junhui Zhao, David Hann, Doug Maguire,
Doug Mainwaring
SNC cause premature loss of foliage,
Foliage retention 1-4 years
(Alan Kanaskie, 2012)
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Swiss Needle Cast affect Douglas-fir
Needle on the left showing rows of black
fruiting bodies of Swiss needle cast.
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(Photo by Bryan Black)
1983 1980
1970
1961
2008:1984
Direction of growth
The trees’ growth between 1984 and 2008 was packed
into just a millimeter.
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Why do we study on this project?
• Swiss Needle Cast (SNC) disease is widely
spread in Douglas-fir plantation in Pacific
Northwest.
• SNC inhibits the growth of Douglas-fir to
varying degrees, depending on SNC severity.
• ORGANON is a popular computer model of
individual tree growth for areas of the Pacific
Northwest. However, the SNC modifier
currently used in ORGANON is believed not
performing well.
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Objective
• To develop SNC modifier for diameter
increment model, and height increment
model in ORGANON.
• Estimate growth loss of individual trees for
Douglas-fir.
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Study plots
• 76 Growth Impact Study
(GIS) plots
• 23 Pre-commercial
Thinning Study (PCT)
plots
• 30 Commercial Thinning
Study (CTP) plots
• 44 Retrospective
Commercial Thinning
Study (CTR) plots
Measurements
• GIS and PCT plots were measured for 4 growth
periods in 10 years, CTP plots were measured
for 2 growth periods in 6 years, and CTR plots
were measured for 1 growth period in 4 years.
• All trees were measured for DBH, a subsample
of trees were measured for height and height
to lowest live crown base.
• 10 trees in a plot were scored for SNC severity,
plot foliage retention is the average of 10 trees.
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Initial foliage retention in different
studies
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ORGANON predictions
• Professor Hann helped me to run his SMC
version of ORGANON using the beginning tree
list to generate the ORGANON expectations
for the next nearest measurement.
• Then I divide the ORGANON expectations of
diameter and height growth by the growth
length to get annual increment.
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Model development
• Develop models for modifier ∆D/ ∆Dpred and
∆H/ ∆Hpred as a function of foliage retention.
• Only trees with measured height and height
to crown base were used to develop modifiers.
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Comparison of observed vs. predicted
diameter annual growth
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Comparison of observed vs. predicted
height annual growth
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Model Forms
• Since the modifier was expected to range
between 0 and 1, we tested the two models:
• β1 is the rate of decrease in the modifier, β2 is
the scale of the modifier, α is a intercept
between 0 and 1.
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Alternative Approach – Approach 1
• Three alternative approach were used to
develop SNC modifier.
• Approach 1: Fit models using GIS data, and all
data respectively, with no distinction between
healthy and unhealthy trees. This approach
will tell us whether it is reasonable to analyze
all 4 studies together or not.
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Rationale for approach 2 and 3
• Presumably, as the SNC population is different
from the ORGANON data set, the SNC effect
may be confounded with an adjustment factor.
We might want to model the SNC modifier
after the adjustment.
• In approach 2, we calculated the adjustment
factor for diameter and height growth model
using healthy trees, and in approach 3, we fit
the ORGANON model using healthy trees.
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Approach 2
1. Estimate an adjustment factor for DGRO and
HGRO for the SNC population based on
“healthy” trees,
2. apply the adjustment factor to estimate
expected DGRO and HGRO for “infected”
trees, and
3. develop a model for estimating a SNC
modifier for DGRO and HGRO as a function of
initial foliage retention.
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Approach 3
1. Fit ORGANON SMC diameter and height
increment model forms using healthy trees,
2. calculate predicted diameter and height
increment for infected trees.
3. develop SNC modifier models using two
alternative model forms.
The cut-off value
• Plots with foliage retention ≥ 3.5 years are
considered as healthy,
• Plots with foliage retention < 3.5 years are
considered as infected.
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Result of Approach 1
Model [1]
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Model [2]
Result of Approach 2
Model [1]
Model [2]
DGRO adjustment factor =1.0883513, HGRO adjustment factor =1.0354867
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Result of Approach 3
Model [1]
Model [2]
Compare results of DMOD
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Growth loss 14%-18%
0.9
M
O
D
0.8
ap1m1_GIS
0.7
ap1m2_GIS
0.6
ap1m1_ALL
0.5
ap1m2_ALL
0.4
ap2m1_ALL
0.3
ap2m2_ALL
0.2
ap3m1_ALL
0.1
ap3m2_ALL
0
FR=0
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FR=1
FR=2
FR=3
FR=4
Compare results of HMOD
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Growth loss 13%-15%
0.9
0.8
0.7
ap1m1_GIS
M 0.6
O 0.5
D
ap1m2_GIS
0.4
ap1m2_ALL
0.3
ap2m1_ALL
0.2
ap2m2_ALL
ap1m1_ALL
0.1
0
FR=0
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FR=1
FR=2
FR=3
FR=4
Volume growth for trees with foliage retention of 1.0
yr as proportion of healthy tree volume growth
0.80
24%-31% growth loss
Proportion
0.75
ap1m1_GIS
0.70
ap1m2_GIS
ap1m1_ALL
0.65
ap1m2_ALL
37%-42% growth loss
0.60
ap2m1_ALL
ap2m2_ALL
0.55
0.50
0
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10
20
30
40
Initial tree DBH (cm)
50
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Discussion
• Maguire et al. (2011) used the same GIS data
to estimate growth loss at stand level,
according to their study, “Assuming negligible
losses in stands with maximum needle
retention (approximately 3.9 years), growth
losses in net periodic annual increment
reached slightly over 50% in stands with the
lowest needle retention (approximately 1
year).”
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Discussion
• Kimberley et al. (2011) studied impact of SNC
on growth of Douglas-fir, concluded “The
cumulative mean reduction was 25% for mean
top height, 27% for basal area, and 32% for
stem volume.”
• Tree ring analysis conducted by Black et al.
(2010) indicate “at the most severely diseased
site Douglas-fir radial growth was reduced by
as much as 85%.”
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Final remarks
• May be it is not reasonable to blend different
studies together for analyzing SNC modifier.
• Because in the same stand, different trees
may have different SNC intensity, therefore,
the growth loss caused by SNC may be
different, that is maybe why results from
permanent plot measurements are quite
different from tree ring analysis.
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On going…
Suggestions?